Panafrican Ocean (Frozen in Time)
In the timeline of Frozen in Time, the world is locked in a stable assemblage of continents formed into one supercontinent known as Pannotia. This V-shaped supercontinent divides the two major oceans of the timeline, the Panafrican Ocean surrounding it, and the Panthalassic Ocean surrounded by it. The two oceans harbour very different flora and fauna, which evolved according to the oceanic environment. While the Panthalassic Ocean was always a shallow sea of a depth of no more than two kilometers, the Panafrican Ocean has consistently been an abyssal plain of mysterious and more conservative creatures. Ediacaran Early Ediacaran, 553 ma As the first faint ray of sunlight from the distant sun appears over the horizon, two Loricatotherium abysmus retreat down from the western shore of Pannotia to the depths of the mid-Panafrican Ocean, over 10 kilometers deep. These meter long stem-arthropods are one of the last known members of the Pelagidraconia, an order of pelagic Anomalocaris-like predators evolving in the warm oceans of the Cryogenian. However, as plate tectonics came to a halt in the alternate Earth, only the Mancipia living near the hydrothermal vents of the heated seafloor can sustain them. They reach the surface only once a year to mate, laying their thousands of eggs on the craggy rock surfaces of the shallow coast, where the new predators of the early Ediacaran cannot reach. Mid morning on an Earth of 20 hour days, and the surface is completely empty other than several species of sponge. These traditional porous body types are successful at the surface because of a recurring theme in evolution. The simplest of body forms are the best adapted to extreme environments, in this case the 5ºC surface waters of the Panafrican coast. Further down, about a kilometer deep, and several chemotrophic bacteria have somewhat heated the seas, the colonies taking in particles and releasing heat as part of their ordinary metabolism. Several primitive comb jellies float around, with no need for an extravagant light display, there being no predators this shallow in in the sea. Five kilometers down, and finally, the seas are teeming with life. Several basic shelled mollusks inhabit any rocks along the benthos, not threatened by predators, their shells being a good enough defense against the survivors of the beginning of the glaciation. Both particle feeding and predatory jellyfish swim around freely in the pelagic zone. The predatory jellyfish can only prey on the creatures of the benthos, however, so they must take caution in not getting themselves stuck while attacking their prey. They feed mostly on vendozoans, including slow-moving Proarticulata and sessile Rangeomorpha. Their venomous stingers are effective against most vendozoans, but their motion is still planktonic and ineffective. Photosynthesising life seems to be absent, though. Almost entirely nonexistent in the Panafrican Ocean, the base of the food chain is exclusively chemical. By the end of the day, the pair of Loricatotherium abysmus have dived down the full ten kilometers. There, they subsist on the few planktonic Mancipia which live there. Hydrothermal vents, however, are extremely abundant in the abysmal zone. A whole zoo of bacteria can survive there, forming the base of this food chain, as in many others. However, this zone of bacteria, plankton, and reclusive predators is about to disappear. Hydrothermal vents are powered by geothermal energy, a source of energy quickly dissipating during the glaciation. Late Ediacaran, 517 Ma Silence is all that is heard before dawn on the eastern shores of Pannotia. A thin layer of ice covers the the surface of the ocean. As the sun rises, the ice begins to melt. Slowly but surely, a Protoverdes crawls up to the surface to bask in the sun for the entire day. This early member of a new group of symbiotic Proarticulata has formed a partnership with cyanobacteria. While the cyanobacteria cover the surface of the vendozoan, making it appear green, they give their surplus of food to sustain the Protoverdes. The vendozoan benefits them in return by bringing them down to warmth when the sun sets, and bringing them back up to the surface at dawn. By mid morning, the ice finally melts. Halfway above the water, the cyanobacteria soak up the faint rays of the ancient sun. Meanwhile, the extreme difference in temperature between day and night means that in the morning large waves caused by the convection due to a difference in temperature, up to ten meters tall, crash up against the cold rocky shores, carrying any planktonic life with them. Included are jellyfish known as Scyphomorpha, forcefully carried up to the surface by the strong ocean currents. Four hours later, and late afternoon on a quickly rotating Earth, it is low tide. On this beach alone, thousands of jellyfish are swept up, helpless as they dry out and are frozen. That is, other than a single species. Protobifistula has two hollow tentacles which can absorb water from melted ice on the rocks. Still, their system is not quite as successful as it seems it would be. The water in their tentacles freezes if the low tide after they are swept up is too late in the day. Today, this relatively rare species, numbering less than two dozen on the beach, is not so lucky. But on a day when the low tide is earlier, while the other jellyfish still lose their water, this species can retain it. At sunset, the world goes silent again. The last surviving jellyfish, Protobifistula, are frozen before the next high tide. The more successful Protoverdes retreats, going down a kilometer or more over the course of the night. The Protoverdes has an additional trick up its sleeve, though. The energy produced by photosynthesis is more efficient than that by absorbing particles, but it cannot last the Protoverdes through the entire night. Instead, during the night, it reverts to the conservative, but less efficient manner of chemotrophism. By the time it reaches the end of its journey, though, the night is almost halfway over. It restarts its journey up to the surface, and the day begins anew. Cambrian Cambrian–Ordovician Extinction, 483 Ma Washed up on the western Pannotian shore are thousands of jellyfish, and a single, final Epitherium, the last stem-arthropod of any kind, a creature of about 40 centimeters. But this time, as the sun rises, the shores are not silent. The faint tapping of dozens of legs gives away the identity of these creatures. These are the Paracimices, a recently evolved group of terrestrial trilobites, breathing through small holes in their exoskeleton, just as insects do. But they are becoming increasingly rare. Living only on these shores, there are only a few remaining species. The one dotting this beach is known as Geluserpo prehiatus. Extremely tolerant to cold, Geluserpo are scavengers, feeding on the massive amounts of washed up jellyfish. Today, however, the Epitherium was a lucky find. This is a day of extreme tides, so the several Geluserpo will fare well. Unlike on the eastern shore, there are no terramedusans. The Terramedusae have simultaneously evolved to scavenge, but on the opposite side of the ocean there are no competition for the endemic Paracimices. But a disaster is beginning, which will result in the extinction of Epitherium, Geluserpo, and even many of the Terramedusae. Shared by both shores of the Panafrican Ocean are the Articulaverdes, the group of photosynthesising Proarticulata which originated as conservative forms such as Protoverdes. On many days, though, the oceans are frozen all day and all night. While this is not one of these days, the fauna certainly reflects it. Crawling along the beach is a highly specialised form of Articulaverdes known as Helminthoverdes. Highly efficient at moving along land due to its dozens of segments, this is a survivor. This species is a unique mix of simple physiology with extreme adaptation, something always winning in the long run. The ten centimeter long worm-like creature conserves the abilities of getting food from photosynthesising cyanobacteria and from chemicals, but, like almost all terrestrial creatures, must absorb water. Just as inefficient as any other creature in a frozen world at finding water, it survives, but just barely. It has an advantage over other terrestrial animals, though. It is a producer. As the oceans freeze over, the situation becomes more and more dire for other animals. Scratched off of the list of living clades are Paracimices, stem-arthropods, dozens of families of jellyfish, and certain sponges and mancipians. Even more conservative, aquatic, groups of Articulaverdes go extinct, along with many of their vendozoan relatives, the Rangeomorpha. Soon, the shores will once again be silent at dawn. The Helminthoverdes will be alone in its world. Category:Ocean